KR20010008166A - Method of making transmitter and receiver in wireless repeater - Google Patents

Abstract

PURPOSE: An apparatus for realizing transmitting and receiving function is provided to improve quality degradation owing to radar fading occurring in forward and reverse directions by giving diversity function to a relay. CONSTITUTION: The apparatus comprises the first and second receiving antennas(6,7). A signal received through the first antenna(6) passes through a bandwidth filter duplexer and is amplified by a low noise amplifier(LNA). The amplified signal is converted into an intermediate frequency signal in a signal processing part(12), and the converted signal is filtered by an SAW filter. The filtered signal is converted into a carrier frequency signal, and is amplified by a high output amplifier(13). The amplified signal is re-transferred through an antenna(9). A signal received through the second antenna(7) is amplified by a low noise amplifier(11), and is delayed by a delay element(12). The delayed signal is vector mixed with the signal received through the first antenna, and is re-transferred through the antenna(9) after the filtering and amplifying processes.

Description

Method and apparatus for implementing transmitter function in mobile communication repeater

In mobile communication networks (PCS, cellular and third generation systems), repeaters have been widely applied as a method for economically extending coverage. The repeater receives the weak base station signal from the base station through the base station facing reception antenna of the repeater, then amplifies and retransmits the signal to the mobile station through the mobile station facing transmission antenna. Conversely, after receiving the mobile station signal from the mobile station facing reception antenna, amplifying and retransmitting the signal to the base station through the base station facing antenna (FIG. 1). Here, the base station opposite transmission and reception antennas are actually the same, which is possible by using the duplex 10 which can separate the transmission and reception signals inside the repeater. This mechanism is the same for a mobile station facing transceiver antenna. The conventional repeater using the aerial is composed of one antenna opposed to the base station and one antenna opposed to the mobile station. In such a conventional repeater, a signal received at one receiving antenna is received through a multipath because there are many obstacles such as a building between a repeater and a base station (or a mobile station). Since the signal received through the multipath has a vector sum at the antenna, even a slight path change (e.g. movement of an obstacle between the base station and the repeater) may cause a significant attenuation of the received signal strength due to the phase difference between the paths. Can be. This phenomenon is called raylay fading. Therefore, the improvement of mobile communication quality by repeater is how to reduce the fading phenomenon. Recently, wireless repeaters for mobile communication have been applied to mobile communication networks in various forms. That is, many wireless repeaters such as home repeaters for homes, small and medium repeaters for servicing small and medium-sized commercial underground in buildings, high power frequency conversion repeaters and microwave repeaters for low-traffic urban and rural areas It is installed and operated. With this quantitative increase, almost no line of sight (LOS) between the base transceiver station antenna and the repeater transceiver antenna, which is a conventional repeater installation concept, has been achieved, and between the repeater (the repeater antenna is several meters from the ground) and the base station. There are many moving obstacles. Accordingly, fading due to obstacle movement between the base station and the repeater as well as fading of the signal strength reaching the repeater due to the conventional mobile station movement occurs. Therefore, it is true that the call quality of the area serviced by the repeater is considerably deteriorated in terms of forward quality as well as the conventional reverse quality degradation compared to the base station service area. In order to overcome such short-term drawbacks, a method having a transmit / receive diversity function has been proposed in the CDMA method (Patent No .: (10-164250-0000) spectrum spreader receiver and repeater), but the implementation is very complicated and the cost of implementation There is a significant shortcoming to apply in actual field because it is very high.

SUMMARY OF THE INVENTION The present invention has a problem that a conventional repeater has by improving the quality deterioration due to the ray lay fading occurring in the forward (relay at the base station) and the reverse (relay at the mobile station) by simply giving a diversity function to the conventional air repeater. In addition, it is further to develop a repeater capable of providing quality 3G mobile communication base station (with forward diversity function) having a maximum transmission speed of 2Mbps.

1 is a conceptual diagram of a mobile communication service using a conventional repeater

2 is a conceptual diagram of a mobile communication service by a repeater in which a function of the present invention is implemented;

3 is a configuration diagram of a conventional repeater

4 is a schematic diagram of a repeater in which a function of the present invention is implemented;

* Explanation of symbols for main parts of the drawings

1. Base station, 2, 6, 7: base station counter antenna of repeater

3, 8, 9: Mobile facing antennas of repeater

4 repeater 5: mobile station

10: duplex, 11: low noise amplifier (LNA)

12: forward signal processor

13: high power amplifier (HPA)

14: reverse signal processing unit

15: time delay element

A schematic diagram of an actual installation example and system configuration of the present invention is shown in FIGS. 2 and 4.

Since a conventional aerial repeater amplifies and retransmits a weak signal between a base station and a mobile station, it is inherently difficult to implement the spatial diversity function adopted by the base station. In addition, the aerial repeater cannot apply the spatial diversity function applied to the base station and the optical repeater directly connected to the optical cable during the relay period. (The optical repeater transmits signals of two paths received from the mobile station to the base station independently through the optical cable. Thus, the present invention uses the time diversity function, that is, the function of the rake receiver, which is an advantage of the CDMA radio access method by connecting to two receiving antenna paths of the base station. In IS-95A / B, there are four rake receivers in the base station receiver, which can demodulate up to four delayed signals from multipath, and there are three such rake receivers in the mobile station. In addition, the IMT2000 base station and the mobile station, which are the third generation systems, have 8 and 6 rake receivers as standard, and in order to improve the quality of high-speed data transmission, not only the reception diversity function but also the transmission diversity function are standard.

In the present invention, the signal reception from the base station is installed so that the receiving antennas 6, 7 of the repeaters are about 10 times the carrier frequency so as to be independent of each other's receiving paths, or alternatively, a polarization antenna (+/-, +45). / -45). The signal received from the first antenna (path 1) is passed through a bandwidth filter duplex and amplified by a low noise amplifier (LNA). The amplified signal is converted to an intermediate frequency (IF) by the signal processor 12 to remove the noise in the received signal and the amplification process, filtered by a SAW filter having a high selectivity, and then again converted to a carrier frequency. After amplification by the high power amplifier 13 as desired, it is retransmitted through the duplex and the mobile station counter antenna 9. The sequence of receiving, amplifying and transmitting up to this point is the same as the conventional RF direct repeater method. The signal received at the base station facing second antenna 7 is amplified by the low noise amplifier 11 to have the same gain as the first path and then delayed the received signal by more than two chips by the delay element 12, i.e., SAW filter or cable. Let's do it. In general, the signal demodulation capability of the rake receiver is more than 1 chip in the CDMA standard. Therefore, the IS-95A / B / C needs a minimum delay of 0.814us and IMT2000 0.32us.

The delayed signal is then vectorly combined with the signal received at the first antenna before the signal processor 12, filtered and amplified like the first signal, and then retransmitted through the mobile station counter antenna 9.

The mobile station can greatly improve forward quality (coverage and frame error rate, etc.) compared to the conventional repeater by receiving two independent signals separated from each other in time from the repeater at the rake receiver and performing demodulation processing. In addition, the forward direction implementation method applied in the present invention may be equally applied to the reverse direction to improve the reverse quality.

First, the effects of the present invention have a significant effect on improving the quality of the service area of the small and medium repeater in operation for solving the underground shadow area in downtown. In general, the coverage of a small and medium repeater is less than 10dBm, so the coverage is highly dependent on the forward characteristics since the forward (base station to mobile station) coverage can be 20dB less than the reverse coverage. In addition, since the base station facing antenna of the small and medium repeater is typically installed within 3 meters above the ground, even though the antenna is fixed, the obstacles (cars, etc.) of the surroundings move, so the signal received from the repeater's antenna experiences ray lay fading in real time. As a result, base station facing antennas of small and medium repeater devices experience significant raylay fading in real time as mobile stations. Therefore, the repeater of the present invention can bring a coverage expansion effect of 2 to 8 dB compared to the same output compared to the conventional repeater. Second, since the present invention can significantly reduce the frame error occurrence rate, which is a measure of CDMA radio quality, compared to the conventional repeater, cdma2000 and W-CDMA, which are third generation systems whose radio quality conditions are 1000 times stronger than those of IS-95A / B. Suitable for service Third, Korean mobile communication companies currently use unused frequency (unused channel) as the link frequency of base station and relay period in their own band and convert unused frequency (unused channel) to operating frequency (operation channel) again in the remote system. The basic method of the frequency change repeater repeating the base station and the mobile station signal and the frequency conversion repeater and the base station and the mobile station signal repeater are the same, but in the case of the microwave repeater in which the link frequency is applied to the microwave, the forward and reverse directions are applied. It can have a significant effect on quality improvement. Fourth, if the present invention (forward diversity function) is applied to the optical repeater, the forward quality equivalent to that of the base stations of the IS-95C, cdma2000, and W-CDMA radio access methods can be obtained. The cost of implementing the diversity function can be reduced by half while bringing the quality improvement effect equivalent to the diversity configuration method. Fifthly, if the present invention is applied to a distributed system for an in-building mobile communication service (optical distributed system, IF distributed system, etc.), the high-speed wireless quality of 2 Mbps of cdma2000 and W-CDMA, which is difficult to provide in a conventional system, may be obtained. Service is possible with quality.

Claims (3)

Repeater implementing transmit / receive diversity in transmitting / receiving signals to / from base station (or mobile station) The repeater of claim 1, wherein the transmit / receive diversity implementation uses a base station and a mobile station rake receiver. A method of using a rake receiver according to claim 2, which implements a simple delay element in the second antennas 7 and 8, combines the signal of the first antenna 6 and 9 in front of the high power amplifier, and transmits one antenna 6 to the base station and the mobile station. 9) transmission method